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KMID : 0383119680160010001
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Journal of Aerospace Medicine
1968 Volume.16 No. 1 p.1 ~ p.19
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Effect of Overcompression -in Dysbarism
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Abstract
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The pathogenesis of dysbarism is not fully established yet, though the nitrogen, bubble theory prevails currently. Accepting this theory as the cause of dysbarism,it has been the aim of the overcompression treatment to eliminate these bubbles from the tissues of the victim Some beneficial effects of the above treatment have already been reported. But no established norm is available as to the optimal pressure to be applied. The .present study was planned to see the physiological effects of overcompressioa and also to find out the optimal value, if there is any, of pressure to be used in the treatmentt of dysbarism.
One hundred and five male rabbits weighing 1, 800-2, OOOgm. were used. Each animal was fixed on an animal board and put into a small decompression chamber which was connected by means of a 2 inch pipe to a 6-man decompression chamber that had already been decompressed to the simulated altitude of 41,000 feet. The animal was decompressed instantly by breaking the cellulose acetate membrane fitted in the connecting pipe. Following, decompression for 90 seconds, the collapsed animal was removed from the low pressure chamber, released from the animal board, and left in the air (Control animal), or thansferred immediately to an overcompression chamber the pressure of which .was rapidly raised to 2, 3 or 4. atmospheres. In the course of decompression and overcompression or return to the ground level, the EEG, EKG, and respiratory rate of the animal were recorded using an Offner type T 8-channel electroencephalograph. Blood g6ses-were: analysed, blood cells counted, and hemoglobin content, hematocrit and specific gravity were measured, before and immediately after decompressionAnd also nduring pvercompression,
Following results were obtained:
1. The recovery time, defined as the time interval between the end of decompression and the moment when the animal stood for the first time on its own feet, was significantly shortened in the over compression groups compared with the value of the control group. The recovery time was shortest in the 2 atmospheric pressure group, the values of the 2,3 and 4 atmospheric pressure groups being 40%, 51% and 63%, respectively, of that of the control group.
2. After termination of decompression, the 2 atmospheric pressure group recovered the earliest from hemoconcentration, which had developed in the course of decompression. In general, the cardiac function recovered earlier than the respiratory movement.
3. EEG changes under decompression, such as appearance of slow wave and flattening of the wave, were restored it 1 or 2 min after the termination of decompression in all groups. No apparent neurological complication was noted during one month´s observation period following the decompression over compression experiment.
From the above results, it is reaffirmed that over composition is effective in the treatment of dysbarism, and that the optimal pressure seems to be 2 atmospheres.
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